The earliest antecedents of immediate loading were introduced by Ledermann in 1979. He placed overdenture in four interforaminal implants on the same day the surgery was carried out. In the original implantological protocol of Brånemark the immediate loading did not appear indicated, currently, it is being presented as a predictable alternative in several studies. We revised different articles on immediate loading from 1997 to 2002. We analysed different variables and concluded that immediate loading produces a success rate in posterior maxilla similar to the differed loading (90-100%). The characteristics of the implant, favourable to immediate loading, are: screw-shaped, with a rough surface, sand blasted and acid etching processed and a minimum length of 10 mm. The initial stability and a micro movement of the implant, inferior to 150 microm and a marginal to the insertion equal or superior to 32 N/cm are defined as a proper osseous. The bruxism stands out as an adverse factor according to several authors.